Anti-G8 demonstrators clashed briefly with Italian police on Saturday in the first big protest ahead of next week's summit of the world's richest nations.
Police in riot gear fired teargas at protesters to prevent them from crossing a bridge and moving closer to a contested US military base in the northeastern city of Vicenza.
The demonstrators, some of them wearing motorcycle helmets and with their faces covered, threw bottles and lit fireworks as they were pushed back on the bridge.
Several thousand people, most of them marching peacefully, attended the rally in protest at expansion plans that would make the US base one of the biggest in Europe and more generally against the next week's G8 summit,
The Italian government has approved construction of a new 6,000 square metre base on the site of the old Molin airport on the city's outskirts.
The leaders of the United States, Japan, Germany, France, Britain, Italy, Canada and Russia, together with those of major emerging economies, will hold talks in the central city of L'Aquila on from 8 July to 10 July, focusing on the state of the world economy, financial regulation, climate change, trade and development.